This invention relates generally to vehicle engine cooling systems and more particularly to a method and apparatus for extracting and using the waste heat thereof.
A number of systems have been invented to extract heat from the liquid cooling circuit of a vehicle engine. Many of the early designs incorporate simple thermostats that direct coolant to a radiator or heater as the coolant temperature rises. For example in 1955, U.S. Pat. No. 2,706,085 issued to Nallinger disclosing a thermostatic regulating device that directs heated coolant to either a radiator or heater depending on the temperature of the coolant. Similarly, in 1966, U.S. Pat. No. 3,246,637 issued to Walsh illustrating a thermostatically controlled cross flow engine radiator with a thermostat controlling the flow direction of coolant depending on coolant temperature. Although each of these designs are provided to keep engine coolant at a predetermined temperature, neither is directed to extracting heat from the coolant to heat water in an auxiliary storage tank.
A few subsequent designs were directed to extracting heat from the engine coolant to heat other equipment. For example in 1970 U.S. Pat. No. 3,521,704 issued to Bridegum disclosing a heat exchanger for recreational vehicles where engine coolant flows through a heat exchanger to heat water in a water storage tank. In 1972 U.S. Pat. No. 3,645,327 issued to Henley disclosing a pipe disposed in a hot water radiator tank for extracting heat therefrom to heat storage water in a separate tank. U.S. Pat. No. 4,162,670, issued in 1979 is directed to a system to extract heat from engine coolant to heat a food warmer assembly. Also U.S. Pat. No. 4,154,669 issued in 1979 discloses a system that extracts heat from engine coolant to heat a secondary water circuit. Each of these designs, however, do not incorporate any means to regulate the amount of heat extracted from the engine coolant to protect the vehicle engine from operating at a improper temperature.
Other more recent designs include U.S. Pat. No. 4,422,572 issued in 1983 which discloses an engine cooling water circulation system that employs a two way valve therein. U.S. Pat. No. 4,556,171 issued in 1985 disclosing a heating system for automobiles with a heat storage tank including electromagnetic valves for selectively introducing the engine cooling water from the engine and the heat accumulating water into the heating radiator. U.S. Pat. No. 4,562,890 issued in 1986 disclosing an apparatus for warming window washer liquid by wrapping the washer hoses around the engine coolant hose. In addition, U.S. Pat. Nos. 5,211,334 and 5,407,130 issued in 1993 and 1995 respectively illustrate heat storage devices for use with motor vehicles wherein each employ a combination of valves to control the flow liquids within the system.
Although the above noted prior art inventions, provide various methods and systems to extract and utilize heat from the coolant of an internal combustion engine, none of the same are directed to, or teach a simple, low maintenance method for extracting heat from the coolant of an engine to heat process water stored in a storage tank while automatically maintaining the proper temperature levels of the coolant and the process water.
Accordingly, a need remains for an inexpensive system designed to safely and automatically extract heat from the coolant of an engine's coolant system to heat process water in an auxiliary water storage tank, while maintaining the engine coolant at its proper temperature for cooling the vehicle engine, and while maintaining the process water at its predetermined desired temperature.